Tom,
Sounds like an incredible deal. I'm paying 8k, but for a 2 bdrm l/o-red. I like your deal better, although we do plan to lock it off every other year and go for two weeks on the even years.
If you are questionable about the clearance of the close, make sure you pay for title insurance. Also, make sure you can get your money back ahead of time if Marriott exercises their First Right of Refusal FROR. Next, be sure the owner secures a week for you right away so you have what you want either for this year or next year.
Best of luck and we hope you enjoy.